The present invention relates to rotary multi-position electro-mechanical switches.
Numerous designs for rotary multi-position switches are available for a variety of applications. A conventional multi-position automobile headlamp switch, for example, includes a rotor shaft with multiple cantilever springs that are attached to the shaft and provide electrical contact with their ends. When the rotor shaft is rotated to various positions, the ends of the springs open and close circuits as they come in contact, via a wiping action, with electrical conductors on the printed circuit board of the switch.
The repetitive wiping action subjects the electrical conductors to wear at high number of cycles. The conductors are also fragile and easily damaged. Therefore, improved switches that avoid direct wiping action on the conductors are still desirable.
The invention provides a multi-position switch assembly. The switch assembly includes a member rotatable about an axis of rotation, a set of first electrical conductors and a set of second electrical conductors. The second conductors are disposed on a printed board circuit at a radius from the axis of rotation. The switch assembly also includes an actuating mechanism that selectively provides electrical contact between at least one of the first conductors and one of the second conductors to close a circuit when the member is rotated.
In one embodiment, the first conductors are stationary. The actuating mechanism for the stationary conductors includes a cam, a retainer with bearings, and a pad with resilient buttons that have conductive portions that incorporate the first conductors. When the member is rotated, the cam selectively forces a bearing against one of the buttons, causing the button to deform and close an electric circuit of the switch assembly.
In another embodiment, the first electrical conductors are rotatable with the member. The actuating mechanism for this embodiment includes springs that are received in retaining portions of the member. The springs bias the first conductors in a guiding slot on the printed circuit board. In this embodiment, the second conductors are pairs of traces placed on opposite sites of the guiding slot. When the member is rotated, the first conductors come in contact with the pairs of traces at pre-determined positions and close a circuit.
Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims.